Michelle Lynn Monaghan was born on March 23, 1976, in Winthrop, Iowa. Her parents are Sharon and Bob-John Monaghan. She has two brothers.
After graduating from high school, she went to Chicago to study journalism. Between studying, she did some modelling in the United States and around the world in Europe (Milan), and Asia (Singapore, Tokyo, Hong Kong.) She became interested in acting and received a few minor parts in episodes of television series Young Americans and Law & Order: Special Victims Unit.
Her big screen debut was in 2001 in PERFUME. In 2002 she appeared in UNFAITHFUL. In the meantime, she continued her modelling career and did some commercials.
Her big break came in 2002 with television series BOSTON PUBLIC in the role of Kimberly Woods. After guest starring for a season on the television series, she turned back to the silver screen and appeared in IT RUNS IN THE FAMILY in 2003 and WINTER SOLSTICE in 2004. Also in 2004 she appeared in The Bourne Supremacy, and then Mr. & Mrs. Smith with Brad Pitt and Angelina Jolie in 2005.
Also in 2005, she landed her first starring role in the black comedy Kiss Kiss Bang Bang alongside Val Kilmer and Robert Downey Jr, and played in NORTH COUNTRY with Charlize Theron, Sissy Spacek, and Frances McDormand.
In 2006, she appeared as the love interest and female lead opposite Tom Cruise in Mission: Impossible III.